Progressive idiopathic anterior dislocation of the upper cervical spine with severe myelopathy.

Three unusual and rare cases are reported with progressive anterior dislocation of the cervical spine of unknown etiology causing severe myelopathy. Spinal pathology was confined to a single level and at different locations in each case. Narrowing of the spinal canal resulted in three different neurological syndromes, each requiring a different operative approach: one anterior, one posterior, and one both. Two patients made complete functional recovery. One patient died 3 days after operation of aspiration pneumonia.